This Shop Kit includes all the popular sizes needed for most aftermarket turbo engines! You'll have the flexibility to test all turbos or at any pipe with an outer diameter of 3 inch, 3.25 inch, 3.5 inch and 4 inch The boost leak tester is designed to fit over the inlet flange of the turbo charger and allows you to pressurize the charge system with compressed air while the vehicle is off. This is an important tool every turbo car owner needs in their arsenal of tools. It will keep the turbo healthy by eliminating leaks in the boost path and not allowing it to over speed compensating for a boost leak. A must if you are tuned or any time you are replacing any components in the intake tract such as charge hoses, intercooler, manifold, vac lines, injectors…etc. Also a must if you are going to the track and want the peace of mind that the turbo wont over-work or risk blowing any hoses off that are loose Includes/Design Features: End Cap - Billet 6061 Anodized Aluminum, 1/8" NPT threaded gauge port & fitting port (4) Silicon Couplers - High quality 4 layer Adaptors Sizes include: 3 inch, 3.25 inch, 3.5 inch and 4 inch Boost Gauge - Custom Stainless Steel 30 PSI / 1Bar – Liquid filled 30 PSI range will give you the appropriate reading when testing your charge pipes for low, medium or high boost levels.